Ten people, including four women and two children, were killed when lightning struck them in different parts of West Bengal state since Sunday, officials said. In the neighbouring state of Bihar, six people were drowned as flash floods inundated farmlands and devastated villages, said Manoj Kumar Srivastava, a senior official.
"At least 83 villages have been affected and we are evacuating people from low-lying areas," Srivastava told reporters on Monday in the state capital, Patna.
Dozens were also injured as strong winds, accompanied by heavy showers uprooted trees and electric poles in the region, witnesses and officials said.
Train services were also disrupted in many places and flight operations hampered by overcast conditions.
Hundreds of people died in a heatwave in May and June that preceded the monsoon.
(Additional reporting by a Reuters reporter in Patna)